Portable power tools



e F d F. S. SJOSTRAND ETAL PORTABLE POWER TOOLS File Feb. 6, 1962 United States Patent @ffice 3,d1,673 Patented Feb. 6, 1962 3,019,673 PORTABLE POWER TOOLS Frltiof Stig Sjtistrand, Stockholm, Carl Otto Lennart Ottosson, Elrtorp, and Stig Rune Zerncll, Johanneshov, Sweden, assignors to Atlas Copco Aktiebolag, Nacka, Sweden, a corporation of Sweden Filed Feb. 17, 195 Ser. No. 793,786 8 Claims. (Cl. 77--7) This invention relates to portable power tools of the gun type having a barrel portion accommodating a motor, an implement-carrying chuck and a handle portion extending downwardly and rearwardlyfrom said barrel portion at an obtuse angle. One object of the invention is to provide a body for a portable power tool which fits a hand holding the tool and producing an axial pressure in the direction of the axis of the barrel. Another object of the invention is to provide a body for a tool having a large rear surface on which pressure may be exerted by a hand holding the tool. Another object of the invention is to provide a body for a portable power tool of the type described which is cheap in manufacture and fits into the hand of an operator in a manner which requires little effort. A further object of the invention is to provide a body for a tool of the above mentioned type in which the feeding of the tool towards the article to be operated on may be carried out without subjecting the hand holding the tool to a bending moment or which subjects the hand or wrist to a very small moment in the two main planes of movement of the wrist. A still further object of the invention is to provide a body for atool of the type described in which the twisting moment of a motor provided in the tool body is taken up by the hand holding the tool with as little strain as possible. A still further object'of the invention is to provide a tool in which the thumb and forefinger are used together for guiding the tool towards the work and the other fingers are used for manipulation of the trigger or its equivalent. A still further object of the invention is to provide a body for a tool of the type described in which a rotary motor and speed reduction gear may be assembled into the tool body from the front end of the body. A further object of the invention is to provide a body for a tool of the type described in which ample space is provided for exhaust silencing means and in which the exhaust air from an air motor is expelled in such a manner that it does not interfere with the hand holding the tool. A still fur th'er object of the invention is to provide a tool of the type described in which the manipulation of controlling means for the tool motor has very little tendency to change the direction in which the tool is held. A still further object of the invention is to provide a tool which when lying on a table is easy to grasp w'th one hand in such a way that the operator immediately obtains the correct grip for operation of the tool.

For the above and other purposes we provide a body for a portable power tool of the gun type having a barrel portion accommodating a motor which may be a rotary air motor, a rotary electric motor, or a reciprocating motor, means for securing a chuck at the front end of said barrel portion, a handle portion extending downwardly and rearwardly from said barrel portion at an obtuse angle, and a projecting wing at each side of said barrel portion extending longitudinally of said barrel portion to form a rest or support for the thumb and forefinger and means for separating said thumb and forefinger from the other fingers of a hand grasping the rear end of the barrel portion and the handle portion, said barrel portion forming a ridge separating said thumb and forefinger. In pneumatic tools of this type we provide a noise dampening chamber in said barrel portion, and exhaust passages in said projecting wings leading from said dampenlng chamber to the atmosphere and opening at the forward ends of said wings. Other features of the invention will appear from the following description of a preferred embodiment of the invention selected for the purpose of illustration only and which should not be considered to limit the invention, the scope of which is set forth in the appended claims.

In the drawing, FIG. 1 is a perspective rear and side view of a pneumatic drill embodying to the invention. FIG. 2 is a front view of the drill illustrated in FIG. 1; FIG. 3 is a perspective plan view of the drill in slightly depressed position. FIG. 4 is a longitudinal section of the drill illustrated in FIGS. 1 and 3 on lines IV-IV in FIG. 2. FIG. 5 is a section on lines VV. FIG. 6 a section on lines VI-VI, and FIG. 7 a section on lines VII--VII of FIG. 4. FIGS. 5-7 are on a reduced scale as compared with FIG. 4. FIG. 8 is a perspective view of a tool embodying the invention lying on a table and shows a hand about to grasp the tool.

The pneumatic drill illustrated in the drawing is pro-l vided with a body which may be cast from a suitable aluminum alloy, artificial resin, or other suitable material and which consists generally of a barrel portion 1 and a handle portion 2 extending downwardly and rearwardly from said barrel portion at an obtuse angle. ,The barrel portion 1 forms projecting wings 3, 4 at each side of the barrel portion extending longitudinally forward ly and separated by a ridge 5 so as to form between them upper concave portions 6 and 7, respectively, in which the forefinger 8 and the thumb 9 of a hand 19 holding the rear part of the barrel and the handle portion 2 of the tool may rest. At the rear end of the barrel 1 and the back of the handle portion 2 a curved portion 11 is formed which fits the palm and the heel of the hand and said portion 11 ends in a lip 12 at the upper end of the barrel. The portion 11 forms a large and broad surface against which the hand presses and which has so large an area that only a moderate pressure per square centimeter is produced. The wings 3 and 4 and the underside 13 of the barrel portion are form-ed rather fiat so as to permit freemotion of the middle finger 14 of the hand 19 so that said finger may be used to manipulate the trigger 15 disposed in the angle included between the barrel portion 1 and the handle portion 2 and having a rectilinear motion in the handle portion directed substantially towards the centre of the wrist of a hand holding the tool. While the thumb and forefinger, when the tool is grasped, guide the tool and hold it carefully in a desired direction, the manipulation of the trigger has no or very little tendency to change such direction. The tool is therefore very easy on the operator and causes but little fatigue even if it is used during long periods.

When the tool rests on a table the balance is such that the tool takes a slightly depressed position as is obvious from FIG. 8. It is therefore possible for the op; erator to get the correct grip on the tool immediately, and it is not necessary for him to change or adjust his grip before he starts to work with the tool, which reduces operating time.

Compressed air is supplied to the tool through a bushing 16 fitted in the lower end of the handle portion 2, and the supply to the motor is controlled by a valve 17 manipulated by means of the trigger 15. A chamber in the handle may be used for providing a suitable lubricant which is conveyed to the compressed air inlet through a wick 19. In the illustrated embodiment 20 is a rotary air motor of the sliding vane type fitted in a bore 21 in the barrel portion 1. Two exhaust chambers 22, 23 surround the cylinder of the motor and communicate with each other through narrow spaces 33 and through restricted passages 24 with a second. exhaust chamber 25 cates a cap covering the front 30 is a tool spindle and 31 a chuck carried by said spindle in which a drill or other working implement The tool is consequently very easy on the hand and causes very little fatigue in operation. The tool is also very easy to grasp when lying the wings do not increase the minimum distance between the tool axis and the surface 5 which defines how close to a wall or a corner the tool may be operated.

The above described tool is only an example and the invention may be modified in several ways within the scope of the claims.

What we claim is:

l. A portable power tool of the gun type having a ban, rel portion accommodating a motor and an implement- Qarrying chuck and a handle portion extending downwa'raly nd' rearwardly from said barrel portion at an obtuse angle, a projecting wing at each side of said barrel portion, extending longitudinally of said barrel portioh to form a rest or support for the thumb and foreportion, and exhaust passages in said projecting wings leadingfroin said dampening means to the atmosphere and opening at the forward ends of said Wings.

2. A portable power tool as defined in claim 1 having a pneumatic motor disposed in said barrel portion, an air and the wings wings. from said second exhaust chamber.

3. A portable power tool of the rel portion accommodating a motor and an implementhandle portion extending downwardly and rearwardly from said barrel portion at an obtuse angle, a motor cylinder in said barrel portion arranged With its axis longitudinally of the axis of the barrel portion, a rotor in said cylinder mounted to rotate about an axis longitudinally of the axis of said barrel portion a projecting wing at each side ofsaid barrel portion close to the bottom of the barrel portion extending longitudinally of the barrel portion to form a rest or support for the thumb and forefinger at the sides of the upper half of the cylinder and means for separating said thumb and forefinger from the other fingers of a hand holding n i said wings and the botsaid barrel and handle portions,

tom of the barrel portion forming a relatively fiat underside, a comparatively broad rear side of said handle portion, directed upwardly and rearwardly, fitting the palm of a hand holding merging into a ridge said pressure surface hand holding the tool.

4. A portable power tool of the gun type having a barrel portion accommodating a rotary pneumatic motor and an implement-carrying chuck and a handle portion extending downwardly and rearwardly from said barrel portion a ridge formed by projecting wing to the bottom dinally of the barrel portion at the said hand holding the tool.

5. A ortable power operated tool of the gun typehaving a barrel portion accommodating a rotary motor and an implement-carry chuck and a handle portion extendbarrel portion to form a rest or support for the thumb and forefinger at the sides of the upper half of the cylinder of a hand holding said barrel and handle portions and said wings be ngridgemotor and said downwardly and rearing a driving connection between said spindle, a handle portion extending wardly from said barrel portion paratively broad pressure surface at theupper rear side of said handle portion merging into a ridge directed, up wardly and rearwardly, said pressure surface fitting the palm of ahand holding said tool, a. projecting, Wing at each side of said barrel portion close to the bottom of the barrel portion extending longitudinally of the barrel portion to form a rest or support for the thumb and forefinger of said hand at the sides of the upper half of the cylinder and a means for holding apart said thumb and forefinger from the other fingers of the hand holding said barrel and handle portions, and a trigger close below said barrel portion and said wings being ridge-shaped and extending laterally of said barrel portion substantially at the handle side of said rotor axis for manipulating said motor.

7. A portable power tool of the gun type having a generally cylindrical barrel portion accommodating a motor having a rotor coaxial with said barrel portion and a handle portion extending downwardly and rearwardly from said barrel portion at an obtuse angle, laterally projecting wings extending longitudinally of said barrel portion at each side thereof, said wings providing with the upper part of said barrel portion concavely rounded and substantially parallel groove-like portions at the bases of the upper sides of the wings for supporting the thumb and forefinger of a hand holding the tool.

8. A tool as defined in claim 7, in which the shaft of said rotor carries an implement-carrying chuck coaxial with the rotor, said groove-like portions of said barrel portion being substantially parallel and coplanar in a plane substantially coincident with the axis of said chuck, whereby the plane passing through the thumb and forefinger of a hand grasping the tool in intended fashion is coincident with or closely adjacent to the axis of said rotor and said chuck, to thereby provide for optimum guidance and application of longitudinally exerted force on the implement operated by the tool, by the hand of the operator.

References Cited in the tile of this patent FOREIGN PATENTS 

